Technologies for using power of an electric car, or the like, have been proposed. An example of Prior Documents disclosing these proposed technologies may include KR Laid-Open Patent No. 10-2009-0119833, or the like.
The methods disclosed in these Prior Documents are a type that uses the integrated power of the electric car, or the like. Describing in detail, the methods are a type that combines each of the electrical resources with the corresponding bridges and connects it with the power grid (referred to as a grid).
However, according to the above-mentioned methods, when the plurality of electric cars is simultaneously charged, a problem occurs in that the reactive power is insufficient. Therefore, when reactive power is insufficient, transmission efficiency of power is reduced and voltage is reduced in the grid. Because of insufficient reactive power, voltage is further reduced due to the reactive power, which may ultimately lead to black-out.
Therefore, apparatuses, such as a synchronous compensator that is a reactive power compensation device, a shunt capacitor, a flexible AC transmission system (FACTS), or the like, have been used.
According to the related art, the expensive reactive power compensation device needs to be mounted in the grid in order to avoid the black-out, which may lead to much cost.